Keeping Time with the Skies — Mastery

Q1. In the chapter opener, Meera is surprised because she had always thought the Moon could only be seen at night. The Moon can in fact be seen during the daytime when

• A. Its illuminated portion is bright enough and it is above the horizon during the day
• B. Only on a new Moon day
• C. Only during a solar eclipse
• D. Only during a lunar eclipse

Q2. Meera briefly wonders if the Moon's not being a full circle is due to a lunar eclipse. The chapter rejects this for which reason?

• A. Lunar eclipses are dangerous to view
• B. Lunar eclipses happen on new Moon days only
• C. Lunar eclipses produce a full circle of brightness
• D. Lunar eclipses are rare and brief, while the Moon's shape changes every night

Q3. Why does the Moon rise about 50 minutes later each day?

• A. While the Earth completes one rotation in 24 hours, the Moon moves ahead in its orbit, so Earth must rotate a little more
• B. The Earth slows down at night
• C. The Moon does not rotate at all
• D. The Sun and Moon move in opposite directions

Q4. In Activity 11.2, as the student turns anti-clockwise with the ball held at arm's length and keeps looking at it, the line separating the illuminated and non-illuminated portions of the ball appears

• A. Straight at all positions
• B. A perfect circle at all positions
• C. Curved at intermediate positions
• D. Coloured red at intermediate positions

Q5. Figure 11.5(a) in Curiosity labels the Moon's positions A to H around the Earth and matches them to days 1, 4, 8, 12, 15, 18, 22 and 26. Approximately how long does the Moon take to go from position A back to position A?

• A. One day
• B. One week
• C. About one month
• D. One year

Q6. In Activity 11.3, Table 11.2 shows the time of the shortest shadow as 12:20 on 22 March, 12:20 on 23 March, and 12:19 on 24 March. The duration of the day from 22 to 23 March, then 23 to 24 March, comes out as

• A. 12:00 hours and 12:00 hours
• B. 48:00 hours and 47:59 hours
• C. 24:00 hours and 23:59 hours
• D. Cannot be calculated

Q7. Why do seasons NOT stay in the same lunar months in successive lunar years of a purely lunar calendar?

• A. Because the Earth's tilt changes each year
• B. Because lunar calendars skip a leap day every century
• C. Because the Moon's orbit changes shape each year
• D. Because the lunar year of 354 days is about 11 days shorter than the 365-day solar year

Q8. In a luni-solar calendar, the 12 lunar months fall short of the solar year by about 11 days each year. Approximately after how many years does the accumulated gap reach close to one full lunar month?

• A. About 2–3 years
• B. About 11 years
• C. About 29 years
• D. About 100 years

Q9. In some Indian luni-solar calendars, the new month starts on the day after the new Moon and ends on the day of the next new Moon. Such calendars are called

• A. Purnimant
• B. Shaka
• C. Saka Vikrama
• D. Amant

Q10. In a regular (non-leap) year of the Indian National Calendar, which months have 31 days?

• A. All twelve
• B. The first six months
• C. The second to sixth months (Vaisakha to Bhadrapada)
• D. Only Chaitra and Phalguna

Q11. Meghnad Saha is associated with all of the following EXCEPT

• A. Chairing the Calendar Reform Committee
• B. Developing the Saha equation
• C. The Saha Institute of Nuclear Physics in Kolkata
• D. Founding the Indian Space Research Organisation (ISRO)

Q12. For festivals based on luni-solar calendars (such as Diwali or Holi), the Gregorian dates from year to year usually shift, but only by

• A. More than a year
• B. More than a month
• C. Less than a month
• D. Exactly seven days

Q13. Which ISRO satellite series captures high-quality images of the Earth used by a mapping platform called Bhuvan?

• A. AstroSat
• B. Aditya L1
• C. Mangalyaan
• D. Cartosat

Q14. Match each Indian space mission with its target as stated in Chapter 11: (P) Chandrayaan 1, 2, 3 (Q) Aditya L1 (R) Mangalyaan

• A. P – Mars; Q – Moon; R – Sun
• B. P – Sun; Q – Mars; R – Moon
• C. P – Moon; Q – Sun; R – Mars
• D. P – Moon; Q – Mars; R – Sun

Q15. A Class 8 student says, 'The phases of the Moon happen because the Earth's shadow falls on it.' Which response by the teacher is the MOST scientifically appropriate?

• A. Praise the answer; it is correct
• B. Tell the student the answer is wrong; do not say more
• C. Use the Activity 11.2 ball-and-lamp model to show that the changing illuminated portion as the Moon revolves causes phases — not Earth's shadow
• D. Tell the student that this is true only during a lunar eclipse

Q16. Activity 11.1 asks the student to begin observing on the first day after the full Moon. At sunrise on this day, in which direction should the Moon be searched?

• A. Western direction
• B. Northern direction
• C. Southern direction
• D. Overhead

Q17. The changing shapes of the bright portion of the Moon as seen from the Earth from one day to another are called

• A. Lunar eclipses
• B. Tides of the Moon
• C. Solar eclipses
• D. Phases of the Moon

Q18. A crescent Moon is best spotted

• A. At midnight in the southern sky
• B. At noon overhead
• C. At sunset directly in the East
• D. Just after sunset in the western sky or just before sunrise in the eastern sky

Q19. The chapter notes that sometimes moonrise occurs in the afternoon (around 2:00–4:00 p.m.). What does this imply for spotting the Moon during the daytime?

• A. The Moon can only be seen at night
• B. The Moon disappears that day
• C. The Moon's phase that day must be new Moon
• D. The Moon can be seen in the eastern sky during daylight on such days

Q20. The apparent periodic motion of the Sun seen by us — rising in the East, setting in the West and rising again the next day — is primarily due to

• A. The Sun moving around the Earth
• B. The Moon's revolution around the Earth
• C. The tilt of the Earth's axis
• D. The rotation of the Earth around its own axis

Q21. Figure 11.8 of Curiosity summarises three cycles that define units of time. Match each unit with the correct cycle: (P) Day (Q) Month (R) Year

• A. P – Moon's revolution around Earth; Q – Earth's rotation; R – Earth's revolution
• B. P – Earth's revolution; Q – Earth's rotation; R – Moon's revolution
• C. P – Earth's rotation; Q – Moon's revolution around Earth; R – Earth's revolution around Sun
• D. P – Moon's revolution; Q – Earth's revolution; R – Earth's rotation

Q22. The Gregorian calendar, which is widely used today, is an example of a

• A. Solar calendar
• B. Lunar calendar
• C. Luni-solar calendar
• D. Sidereal calendar

Q23. The time between successive spring equinoxes is called the tropical year. Which calendar mentioned in the chapter is based on the tropical year?

• A. A purely lunar calendar
• B. A purely sidereal calendar
• C. The Gregorian calendar
• D. An intercalary calendar

Q24. According to the Surya Siddhanta verse cited in the chapter, the Sun's apparent northward progress (Uttarayan) lasts six months from its entry into

• A. The constellation Capricorn (Makar)
• B. The constellation Cancer (Kark)
• C. The Pole Star
• D. The Saptarishi

Q25. Holi is celebrated on the

• A. New Moon of Kartika
• B. Tenth day of Ashwina
• C. Full Moon of Vaisakha
• D. Full Moon of Phalguna

Q26. After their useful life, many artificial satellites and their rocket parts become 'space junk' or space debris. According to the chapter, what happens to small and large pieces of this debris when they fall towards the Earth?

• A. Both small and large pieces always burn up completely
• B. Both small and large pieces always crash on the ground
• C. All pieces stay in orbit forever
• D. Small pieces burn up in the atmosphere; larger pieces can crash on the ground

Q27. A Class 8 teacher wants the BEST hands-on demonstration to help students understand why the Moon's appearance changes over a month. Which of the following is the most effective first activity to use?

• A. A debate on whether the Moon glows
• B. A worksheet listing the names of the phases
• C. Reading aloud and asking students to memorise the terms
• D. Activity 11.2 — a soft ball on a stick held in different positions around the head while a torch shines on it

Q28. A Class 8 teacher wants students to see, in real life, how Indian festival dates connect with the phases of the Moon. Which classroom resource is most appropriate for this purpose?

• A. Only the Gregorian wall calendar
• B. A weather forecast
• C. The Rashtriya panchang published annually by the Positional Astronomy Centre
• D. A railway timetable

Q29. Exercise statement: 'Calendars are based on various astronomical cycles which repeat in a predictable manner.' This statement is

• A. True — day, month and year units come from rotations and revolutions
• B. False — calendars are arbitrary inventions
• C. True — only for Gregorian calendars
• D. False — only sidereal calendars are based on cycles

Q30. Amol was born on 6 May on a full Moon day. Will his birthday fall on a full Moon day every year?

• A. Yes — because 6 May is fixed by the Gregorian calendar
• B. Yes — because 12 lunar months always equal 365 days
• C. No — because full Moons happen only once every 5 years
• D. No — because full Moon dates are tied to the lunar cycle of about 29.5 days, while 6 May is fixed in the solar (Gregorian) calendar